Immune globulin products from human plasma were first used in 1952 to treat immune deficiency. Initially, intramuscular or subcutaneous administration of immunoglobulin isotype G (IgG) isolated from plasma were the methods of choice. However, these methods did not allow for the administration of larger amounts of IgG necessary for effective treatment of various diseases. Accordingly, IgG products that could be administered intravenously were developed. Usually, intravenous immunoglobulin (IVIG) contains the pooled immunoglobulin G (IgG) immunoglobulins from the plasma of more than a thousand blood donors. The preparations usually contain more than 95% unmodified IgG, which has intact Fc-dependent effector functions and only trace amounts of immunoglobulin A (IgA) and immunoglobulin M (IgM). Typically, IVIGs are sterile filtered and the manufacturing process contains steps to inactivate and/or remove viruses. These purified IgG products are primarily used in treating three main categories of medical conditions: (1) immune deficiencies: X-linked agammaglobulinemia, hypogammaglobulinemia (primary immune deficiencies), and acquired compromised immunity conditions (secondary immune deficiencies), featuring low antibody levels; (2) inflammatory and autoimmune diseases; and (3) acute infections.
Specifically, many people with primary immunodeficiency disorders lack antibodies needed to resist infection. In certain cases these deficiencies can be supplemented by the infusion of purified IgG, commonly through intravenous administration (i.e., IVIG therapy). Several primary immunodeficiency disorders are commonly treated in the fashion, including X-linked Agammaglobulinemia (XLA), Common Variable Immunodeficiency (CVID), Hyper-IgM Syndrome (HIM), Severe Combined Immunodeficiency (SCID), and some IgG subclass deficiencies (Blaese and Winkelstein, J. Patient & Family Handbook for Primary Immunodeficiency Diseases. Towson, Md.: Immune Deficiency Foundation; 2007).
While IgG treatment can be very effective for managing primary immunodeficiency disorders, this therapy is only a temporary replacement for antibodies that are not being produced in the body, rather than a cure for the disease. Accordingly, patients depend upon repeated doses of IgG therapy, typically about once a month for life. This therapy places a great demand on the continued production of IgG compositions. However, unlike other biologics that are produced via in vitro expression of recombinant DNA vectors, IgG is fractionated from human blood and plasma donations. Thus, the level of commercially available IgG is limited by the available supply of blood and plasma donations.
Several factors drive the demand for IgG, including the acceptance of IgG treatments, the identification of additional indications for which IgG therapy is effective, and increasing patient diagnosis and IgG prescription. Notably, the global demand for IgG more than quadrupled between 1990 and 2009, and continues to increase at an annual rate between about 7% and 10% (Robert P., Pharmaceutical Policy and Law, 11 (2009) 359-367). For example, the Australian National Blood Authority reported that the demand for IgG in Australia grew by 10.6% for the 2008-2009 fiscal year (National Blood Authority Australia Annual Report 2008-2009).
Due in part to the increasing global demand and fluctuations in the available supply of immunoglobulin products, several countries, including Australia and England, have implemented demand management programs to protect supplies of these products for the highest demand patients during times of product shortages.
It has been reported that in 2007, 26.5 million liters of plasma were fractionated, generating 75.2 metric tons of IgG, with an average production yield of 2.8 grams per liter (Robert P., supra). This same report estimated that global IgG yields are expected to increase to about 3.43 grams per liter by 2012. However, due to the continued growth in global demand for IgG, projected at between about 7% and 13% annually between now and 2015, further improvement of the overall IgG yield will be needed to meet global demand.
A number of IgG preparation methods are used by commercial suppliers of IgG products. A common problem with the current IgG production methods is the substantial loss of IgG during the purification process, estimated to be at least 30% to 35% of the total IgG content of the starting material. One challenge is to maintain the quality of viral inactivation and removal of impurities which can cause adverse reactions, while improving the process efficiency to increase the yield of IgG. At the current production levels of IgG, what may be considered small increases in the yield are in fact highly significant. For example at 2007 production levels, a 2% increase in efficiency, equal to an additional 56 milligrams per liter, would generate 1.5 additional metric tons of IgG.
In the fourth installment of a series of seminal papers published on the preparation and properties of serum and plasma proteins, Cohn et al. (J. Am. Chem. Soc., 1946, 68(3): 459-475) first described a method for the alcohol fractionation of plasma proteins (method 6), which allows for the isolation of a fraction enriched in IgG from human plasma. Several years later, Oncley et al. (J. Am. Chem. Soc., 1949, 71(2): 541-550) expanded upon the Cohn methods by publishing a method (method 9) that resulted in the isolation of a purer IgG preparation.
These methods, while laying the foundation for an entire industry of plasma derived blood proteins, were unable to provide IgG preparations having sufficiently high purity for the treatment of several immune-related diseases, including Kawasaki syndrome, immune thrombocytopenic purpura, and primary immune deficiencies. As such, additional methodologies employing various techniques, such as ion exchange chromatography, were developed to provide higher purity IgG formulations. Hoppe et al. (Munch Med Wochenschr 1967 (34): 1749-1752), Falksveden (Swedish Patent No. 348942), and Falksveden and Lundblad (Methods of Plasma Protein Fractionation 1980) were among the first to employ ion exchange chromatography for this purpose.
Various modern methods for the purification of immunoglobulins from plasma employ a precipitation step, such as caprylate precipitation (Lebing et al., Vox Sang 2003 (84):193-201) and Cohn Fraction (I+)II+III ethanol precipitation (Tanaka et al., Braz J Med Biol Res 2000 (33)37-30) coupled to column chromatography. Most recently, Teschner et al. (Vox Sang, 2007 (92):42-55) have described a method for production of a 10% IgG product in which cryo-precipitate is first removed from pooled plasma and then a modified Cohn-Oncley cold ethanol fractionation is performed, followed by S/D treatment of the intermediate, ion exchange chromatography, nanofiltration, and optionally ultrafiltration/diafiltration.
Despite the purity, safety, and yield afforded by these IgG isolation methods, the yield of IgG recovered from plasma can still be improved. For example, Teschner et al. report that their method results in an increased IgG yield of 65% (Teschner et al., supra). As reported during various plasma product meetings, the average yields for large-scale preparation of IgG, such as from Baxter, CSL Behring, Upfront Technology, Cangene, Prometric BioTherapeutics, and the Finnish Red Cross, range from about 61% to about 65% in the final container. Although better than methods previously employed, this amount of IgG recovery still represents a loss of at least about a third of the IgG present in the pooled plasma fraction during the isolation process.
Due to the limited supply of plasma available for the manufacture of plasma-derived products, the isolation of several blood proteins from a common starting plasma pool can be achieved by integrating the purifications into a single framework. For example, IgG is commonly enriched through the formation of a Cohn Fraction II+III precipitate or Kistler-Nitschmann precipitate A, the corresponding supernatants of which are then used for the manufacture of alpha-1-antitrypsin (A1PI) and albumin. Similarly, several methods have been described for the manufacture of Factor H from by-products formed during the manufacture of IgG immunoglobulins, including WO 2008/113589 and WO 2011/011753.
As such, a need exists for improved and more efficient methods for manufacturing therapeutic IgG products. Furthermore, these methods should also allow for the manufacture of additional plasma-derived products from a single plasma source. The present invention satisfies these and other needs by providing IgG isolation methods that produce yields that are approximately 20 to 25% higher than currently achievable, as well as IgG compositions provided there from. Advantageously, the methods provided herein allow for the co-isolation of other therapeutically important plasma-derived proteins, including alpha-1-antitrypsin (A1PI), Factor H, inter-alpha-inhibitor proteins (IaIp), Prothrombin complexes, Factor VII (FVII), Factor VIII (FVIII), antithrombin III (ATIII), fibrinogen, butyrylcholinesterase, and others.